fn main() {
    function1();
    function2(1, 2);
}

fn function1() {
    println!("函数");

    let mut num = function2(1,1);
    println!("num={}",num);
}

// fn function2(a: i32, b: u32) {
fn function2(a:i32, b:i32) -> i32 {
    return a +b;
}
